Electrical musical instrument



Jan. 29, 1952 J. M. HANERT ELECTRICAL MUSICAL INSTRUMENT 6 Sheets-Sheet1 Filed June 11. 1 947 i te Jan. 29, 1952 J HANERT 2,583,566

ELECTRICAL MUSICAL INSTRUMENT Filed June 11, 1947 6 Sheets-Sheet 2 Jan.29, 1952 HANERT 2,583,566

ELECTRICAL MUSICAL. INSTRUMENT Filed June 11. 1947 6 Sheets-Sheet C5 2282 3/ 254 o /.?0 2 Ll? Jan. 29, 1952 J. M. HANERT 2,583, 65

ELECTRICAL MUSICAL INSTRUMENT Filed June 11, 1947 6 Sheets-Sheet 4 LONGARTIFICIAL LINE VIBRA T0 APP/IRA TUE PEEHMFL IF/EB PEDAL SY/YCHEOA/OUS IMOTOE/ I 540 V/BPHTO VIBE 7'0 Jan. 29, 1952 M H ERT ELECTRICAL MUSICALINSTRUMENT 6 Sheets-Sheet 5 Filed June 11, 1947 6 Sheets-Sheet 6 FiledJune 11. 1947 ENE murm .HDPHD D Dz D U um Swank. 59:5 bmEh Patented Jan.29, 1952 ELECTRICAL MUSICAL INSTRUMENT John M. Hanert, Park Ridge, 111.,asslgnor to Hammond Instrument Company, Chicago, 111., a corporation ofDelaware Application June 11, 1947, Serial No. 753,993 21 Claims. (01.84-125) My invention relates to electrical musical instruments of thekeyboard type such as organs.

The primary object of my invention is to produce with but a single setof tone generators the many extremely important and pleasing musicaleffects achieved by having vibratos of differing extents present in thevarious elements of a complex musical sound such as a solo with apolyphonic accompaniment. These differential vibrato effects aresomewhat akin in their artistic aspects to theatre stage lighting. Forinstance, in a ballet scene in which there is a solo dancer with manysubordinate dancers the dramatic and artistic effect of the solo danceris seriously reduced when the stage with all its dancers is uniformlyilluminated as compared with providing a spotlight for the solo dancerand maintaining the illumination for the subordinate dancers at arelatively low intensity. Similarly the effectiveness of a musical solois very seriously reduced when both the solo and the accompanimentcontain a uniformly large vibrato as compared with the superior effectof a large vibrato on the solo voice with a small vibrato, or novibrato, at all, on the accompaniment. For instance, the effect of alarge vibrato in a violin solo with contrasting non-vibrato harpaccompaniment is one of the most effective instrumentations. Anotherequally eflective instrumentation in the opposite sense is that of anon-vibrato clarinet solo played in contrast with a large vibratopolyphonic violin accompaniment.

The use of a large vibrato in all the tones of an organ produces acharacteristic "theatrical eflect and while this effect is useful forcertain highly animated types of music, it is nevertheless unsuited formore serious music and particularly for church and classical organmusic. Furthermore, the effect of a heavy vibrato in all the tones tendsto produce a vibrato frequency throbbing efiect which is out ofcharacter for serious music. Experiment has shown that if the vibratoeffect must be used on all of the organ tones for classical music itbecomes necessary to so reduce the extent of the vibrato that itscharacteristic tonal warmth is almost absent. If, on the other hand, theaccompaniment and pedal tones are sounded with no vibrato or with but asmall vibrato, the solo tones may be sounded with a very large and richvibrato. In the latter case, the vibrato becomes a highly artisticdevice not only as a means for providing emotional warmth to'the solo,where it is wanted, but also as a valuable means for affording contrastand distinctness between the solo and the accompani- 2 ment. Thethrobbing effect becomes negligible because only a small proportion ofthe acoustic energy is being vibrato frequency modulated.

The listener finds it very easy to distinguish the solo voice (even itspitch lies between other accompaniment notes which otherwise would maskit) if its vibrato is in contrast with the accompaniment. This islikewise true when the solo has no vibrato and is in contrast with therich vibrato accompaniment. It appears that the ear is extremelysensitive to vibrato and can detect this efiect even when it isassociated with relatively soft tones in the masking presence of a largenumber of accompaniment tones provided that the latter are of difierentvibrato character.

In very large pipe organs, a difierential effect has been sought, atgreat expense, by providing separate tremulants for the solo andaccompaniment manuals. This has entailed the necessity of providingseparate ranks of pipes for the solo and accompaniment. Likewise in theorchestra the differential vibrato effect is produced with separateinstruments. Thus, in the past, the amount of primary generatingequipment had to be doubled in order to produce the difierential vibratoeffect. According to the principles of the invention, a single set ofgenerators (such as those disclosed in the electric organ shown anddescribed in Patent No. 1,956,350 to L. Hammond) is used as a unitarytonal generating source for both vibrato and non-vibrato tones.

In order to achieve these highly desirable effects by this economicalmeans the tones should be initially generated substantially devoid ofvibrato and the vibrato producing means preferably takes a form similarto the electrical phase modulation vibrato apparatus described in myPatent No. 2,382,413. With this phase vibrato apparatus and a single setof generators having little or no vibrato in their generated outputs,the high desirable efiects of differential vibrato are perfectlyachieved. When one hears music played on this differential vibrato organit is indeed hard to believe that the same primary generators areproductive of a smooth steady non-vibrato horn solo tone as well as ascintillating vibrato string accompaniment. The undesired unified organefiect is completely obliterated and the listener senses a plurality ofinstrumental sources, as in an orchestral ensemble, even though there ispresent only a single tone generating means.

Another important object of my invention is to provide many new andinteresting organ tone .qualities in which a differential vibrato isapplied to the various harmonic overtones of the tone produced whenplaying but a single key. These harmonic vibrato effects are mostreadily achieved by using the above mentioned electric organ apparatus,in which separate intensity controls are provided for the individualpartials making up the various tone qualities. When using the electricalphase modulation vibrato apparatus and the apparatus of this invention,it is possible selectively to sound any harmonic with a vibrato ofcontrollable extent on either or both of the manuals without increasingthe number of generators, key switches or otherwise materiallyincreasing the cost of the instrument.

Under these conditions the musical tones produced strongly suggest aplurality of instrumental sources. For instance, a vibrato tone qualityon all harmonics except the second (octave) strongly suggests the effectof orchestral strings with glockenspiel. This is because theglockenspiel is a relatively pure tone usually sounded at the octave anddoes not have vibrato. Similarly a non-vibrato fundamental in thepresence of other vibrato overtones when played staccato stronglysuggests the organ accompanied by a marimba or piano. Flute-like solotones of exquisite beauty may be employed in which the fundamental hasvibrato and the third harmonic has no vibrato, and vice-versa. Thus,having the vibrato selectively available on the various partials enablesthe organist to extend enormously the number of beautiful tonal effectsobtainable.

Another important object is to provide an organ in which the vibratoeffect is selectively available on the preset combination switches,making a single operation on the part of the player productive of a newharmonic series with vibrato preselection on all the partials.

Other objects will appear from the following description, referencebeing had to the accompanying drawing in which:

Figures 1a and 1b together constitute a schematic wiring diagram of oneform of the invention;

Figure 2 and 20. together constitute a schematic wiring diagram of asecond embodiment of the invention;

Figure 3 is a block diagram illustrating the broader aspects of theinvention in a generalized form;

Figure 4 is a schematic wiring diagram illustrating another modifiedembodiment of the invention; and

Figures 5 and 6 are block diagrams illustrating the broader aspects ofother modified forms of the invention.

The invention may be embodied in a wide variety of forms but isparticularly adapted for use in electric organs of various types such,for example, as that illustrated in the patent to Laurens Hammond No.1,956,350.

In Fig. 3 the invention is illustrated in generalized form. In itsbroader aspects the invention comprises an electrical tone signalgenerator I00 which is under the control of playing key operatedswitching means IOI and I02, the switching means IOI directingtransmission of the signal produced by the generator I00 to anartificial line vibrato apparatus I04 and thence to an output systemI06, while the switching means I02 causes transmission of the signalfrom the generator I00 directly to the output system I06. The artificialline vibrato apparatus is preferably of the type disclosed in my priorPatent No. 2,382,413 and the output system will in general include anamplifier coupled either to a radio broadcasting system or to anelectroacoustic translating means. The signal provided by the generatorI00 is one of constant frequency during the playing of a note, that is,it includes little if any vibrato. The generator may, however, be onewhich is made to provide different frequencies upon operation ofdifferent playing keys. Its important feature is that the tone frequencysignals which it produces are substantially free of vibrato. Thus thegenerator I00 may be a tunable vacuum or gas tube oscillator, a rotaryor vibratory mechanical-electrical generator, or a pickup of a recordedsignal (either phonographic, photoelectric, capacity, orelectromagnetic). The generator I00 may be a single generator or aplurality of more or less independent generators of any of the abovetypes, one for each tone frequency in the gamut of the instrument.

The playing key operated switching means IOI, I02 in an elemental formmay be simply two switches operated by one playing key or by playingkeys of the same or different manuals. In most uses of the inventionthese switching means will assume one of the following forms: (a) Twokeyboard manuals, one supplying all of its output through the vibratoapparatus I04 and the other supplying its output directly to the outputsystem I06. In such system the solo part of the selection may be playedon the manual which is connected to the vibrato apparatus while theaccompaniment is played on the other manual with small or no vibrato, orvice versa. (b) The switching means may include a number of pre-set keysby which some of the partials of each of the tones controlled by aparticular key are transmitted through the vibrato apparatus I04 whileother partials are transmitted directly to the output system I06. (0)The switching means may include one or two manuals and a plurality ofdrawbars, one for each partial, the drawbars being operable selectivelyto transmit their respective partials to the output system eitherdirectly or through the vibrato apparatus I04.

Other switching devices and arrangements may be employed but theinvention will be described herein as it is embodied in a two manualelectric organ of the type disclosed in said Patent No. 1,956,350.

The artificial line vibrato apparatus is preferably of the type shown inFigs. 2, 2a, 2b and 2c of my prior patent, but may assume a variety ofother forms some of which are shown in other figures of said patent. Thefundamental requirement of this apparatus is that it be capable ofchanging a signal of constant audio frequency into a signal in which thefrequency changes at a vibrato rate and to a vibrato extent withoutsubstantial distortion. It preferably includes selectively operatedmeans to change the extent of the frequency or phase modulation, toproduce a small, medium, or large vibrato effect. The vibrato apparatuswill usually include an amplifier for the input signal, and apreamplifier for the output signal.

The output system I06 will usually comprise a number of stages ofamplification provided with means to mix the two input signals withoutsubstantial distortion. It may also include volume and tone controls. Inthe usual use of the invention it will include one or more speakers.

In Fig. 1a the electrical generating system is illustrated as comprisinggenerators having rotors 31, 49, 56, 65, 68 and I3 generatingrespectively the fundamental and second, third, fourth, fifth, sixth andeighth harmonics. These rotors arenreicrably' or. soft iron havinguniformly sermm Peripheral edges and rotated at appropriate, speeds soas to induce in pickup coils IIO, wound on. permanent magnets II2, therequired rrequency for the above mentioned partials of middle C. Each ofthe pickup coils IIO has one terminal connected to ground and has aplurality of; relatively high valve decoupling resistors RI I4 connectedto its other terminal. The resistors are suitably connected to switchesII6 operated by a playing key C3 of the upper manual andsimilar-switches II6 operable by a similar key of the lower manual. Someof the resistors RII4 are suitably connected to the switches II6 of the:bass pedal CI. Upon depression of the key; C3, (and other keys) of theupper manual the switches I.I6 operated thereby respectively makecontact-with bus bars I20 to I26, while the key switches of; the lowermanual make contact with bus bars. I130. to I36 respectively.

A plurality of preset combination keys I40, I are provided for each ofthe manuals, each of these keys operating switches I44. The switches I44operated by key I40 make contact with bus bars I20 to I26, while thoseoperated by key I4I make contact with bus bars I30 to I36 respectively.

Conductors attached to the switches I44 may be connected to any one of aplurality of binding posts I46, I41. The binding posts l4'6 areconnected through busses I48 to suitably spaced taps on the primary of amatching transformer I50, while the binding posts I41 are connectedthrough busses I49 to spaced taps on the primary of matching transformerI5I. The upper manual is provided with preset key I52 while the lowermanual is provided with a similar preset key I53, these keys beingarranged to operate switches I56 and I51 respectively which cooperatewith the bus bars I20 to I26 and I30 to I36 respectively. The switchesI56 are connected to the drawbars I58 by which a contact is selectivelymade to any one of the busses I48, and similarly switches I51 areconnected to drawbars I59 which operate selectively to connect theswitches I51 to any one of the busses I49. The key switches II6 for thepedal CI which control the transmission of the upper three harmonics,are adapted, upon depression of the pedal to make contact with a bus barI82 while those for the lower order partials are adapted to make contactwith a bus bar I64.

The bus bars I62 and I64 are respectively connected to drawbars I66which may be moved so as selectively to connect the bus bars I62 and INtoany one of a plurality ofbusses I68, the latter being connectedrespectively to the taps on the primary of transformer I5I.

It is important to note that the preset keys I40 and I52 for the uppermanual are provided with a suitable mechanism which prevents more thanone of these keys from being depressed at the same time, the mechanismalso providing a latching means to maintain the key depressed. A similarmechanical arrangement is provided for the preset keys MI and I 53. Itwill be understood that, while for each manual only one preset key suchas I40, MI is shown in the drawing, any desired number may be provided.Likewise the keys I52, I53 and their associated drawbar mechanlsms incircuits may be duplicated if desired.

The secondaries of transformers I50 and I5I are connected betweenconductors I and HI respectively and ground, it being noted that theseconnections are made so that the signals on these two conductors whichare derived from the same generator will be 180 out of phase.

Each of the conductors I10 and "I is connected to ground through asuitable attenuating filter mesh, each mesh comprising capacitors CI12,CH3, resistors RI'I4, RI15 and RI16, in-v ductance LI18 and variableresistors Rl'l9. The variable resistors RI 19 are shown as mechanicallyinter-connected for operation by a single expression pedal I11 (volumecontrol), but if desired, may be provided with separate swell pedals orother suitable volume controls. The conductor I10 is connected to amovable switch arm I00 (Fig. lb) while the conductor MI is connected toa similar switch arm I8I, the switch arm I normally engaging a contactI82 and movable by a cam actuator I83 to engage a contact I84. In asimilar way the switch arm I8I normally engages contact I85 but may becammed to engage a contact I81. The contact I82 is connected to amovable switch arm I38 which normally engages a contact I90, but whenthe mechanical actuator I83 is moved to the right the arm I88 is flexedinto engagement with contact I92, and away from contact I90.

When the switch actuator I63 is in its central position, as shown in thedrawings, a. circuit is completed from theconductor I10, through switchcontacts I80, I82, I88 and I90 to an attenuating network includingcapacitor CI94 and resistors RI95. Rl96- and RI91 to the input of apentode- I98. Similarly, under these conditions, a circuit is completedfrom the conductor I1I through switch contacts I8I, I85 to anattenuating network comprising capacitor C200 and resistors R20l andR202 to the input of a pentode I99.

The pentodes I98, I99 have their cathodes connected to ground through acommon self -bias resistor R204, the cathodes being connected to theirrespective grids through capacitors C206 and C201 and their inputcircuits including control grid resistors R2l0, R2I I' respectively. Thejunction of resistorsRI91 and R2 I0 is connected to ground throughresistor R2I2 in series with a capacitor C2. The junction for resistorsR202 and R2I I is similarly connected to ground through resistor- R2I3and capacitor C2I5. The screen grids of the pentodes I98 and I99 arecoupled by a capacitor CH6 and are supplied with a suitable operatingpotential from a +B source through resistors R2l8 and R219 respectively.The plates of the pentodes I98 and I99 are connected to the +B sourcethrough load resistors R220 and R22 I. The signal on the plates of thesepentodes is supplied to a push pull amplifier 224 through blockingcondensers C226 and C221.

The output of the push pull amplifier 224 is illustrated as beingtransformer coupled to an artificial line vibrato apparatus 226 which,as previously mentioned, may be of the type shown in my prior Patent No.2,382,413. This vibrato apparatus preferably is provided with a vibratoextent control 228, which is illustrated in my aforesaid patent, andwhich may comprise groups of multiple switches for changing theefiective length of the artificial line, thereby changing the degree ofphase and hence frequency modulation effected by the apparatus.

The output of the vibrato apparatus 226 is supplied through a suitablenetwork including capacitors C230 and C232, resistors R234, R235, R236and R231 to the grid of a pentode 240. The pentode 240 in cooperationwith pentode 24! is elfective to change the single ended output of thevibrato apparatus into a push pull output for supplying a poweramplifier 242 which in turn may energize a speaker 244. The cathodes ofthe pentodes 240 and 24I are connected to ground through a commonself-bias resistor R246 while the cathodes are respectively connected totheir control gridsby capacitors C248 and C249. The input circuit forthe pentode 24I also includes a series connection of its control grid toground through resistors R250, R25I and capacitor C252. The screen gridsof the pentodes 24I are coupled by a capacitor C254 and the screen gridsand plates are supplied with suitable operating potentials from a +3source through voltage dropping resistors R256 and R251 and loadresistors R258 and R259.

Thus under the conditions previously discussed, that is, with the switchactuator I83 in its central position the outputs of both manuals of theinstrument will be transmitted through the artificial line vibratoapparatus and thus a vibrato effect will be obtained on the musiccontrolled by both manuals.

When the switch actuator I83 is moved to the left the conductor I10 isconnected to the input of pentode I99 by closure of the switch I80I84and the conductor IN is connected to the input of pentode 2M by virtueof the closure of switch I8II81. This latter circuit includes anattenuating network comprising resistors R260, R26I and R262 and seriescapacitor C264. When the switch is in this condition the signalssupplied to the transformer I50 are transmitted to the pentode I99which, due principally to the coupling of the screen grids of pentodesI98 and I99 by the capacitor C2I6, changes the single signal to a pushpull signal suitable as an input for the push pull amplifier 224, andthis signal, after passing through the vibrato apparatus 226, isimpressed upon the grid of pentode 240. On the other hand, as previouslyindicated, the signals supplied to the transformer HI and transmittedthrough conductor I1I are impressed upon the control grid of the pentode24I. By virtue of the fact that the connections to the secondaries oftransformers I50-I5I are reversed the signals, derived from any singlegenerator, appearing on the control grids of pentodes 240 and 24I are inopposite phase and these tubes thus provide a suitable push pull inputfor the power amplifier 242, the signals being transmitted to thisamplifier through blocking capacitors C266 and C261.

A simplified tone control comprising resistors R268 and R269 is adaptedto be coupled across the input of the power amplifier 242 in series witha capacitor C210 by selective operation of a three position switch 212.Thus the signals produced by the rotating generators will appear in thepower amplifier 242 and will be translated into sound by the speaker 244with a vibrato efiect added to the signals supplied through transformerI50, while the signals supplied through transformer II will appear assound Without the vibrato efiect. Therefore the desired effect ofcontrast between the music played on one manual and that played on theother manual (or a contrast between various partials of tones) isreadily obtained.

When the switch actuator I83 is moved to the right of its centralposition, it will be readily apparent that the conductor I10 isconnected to the input of pentode 24I while conductor IN is connected tothe input of pentode I99. Thus, in general the music produced under thecontrol of the upper manual will not have the vibrato effect whereasthat produced under the control of the lower manual will have thevibrato added thereto.

It is essential that when the switch is displaced from its centralposition in either direction, that is, when only a part of the signalspass through the vibrato apparatus, that the signals appearing upon thecontrol grids of pentodes 240 and MI be of opposite phase and thisresult may be obtained, as previously indicated, by reversing theconnections on the secondary winding of one of the transformers I or I5Ior by utilizing an additional phase inverting device in some otherportion of the circuit.

The apparatus and circuits shown in Figs. la and 1b may assume a numberof variants and may be utilized with or without some of the componentsshown. For example, it is not essential that arrangements be made sothat the conductors from the preset switches I44 be capable of selectiveconnection to both the binding posts I46 and the binding posts I41,since results which are highly desirable from a musical point of viewmay be obtained if all the partials of a single complex tone under thecontrol of a single key have the vibrato added or not, provided that theplayer has the option of having the vibrato in the complex tonesproduced under the control of the playing keys of the other manual.

The invention may be embodied in a more versatile form such as shown inFigs. 2a and 2b. In these figures there are illustrated 9 generators,numbers I, 20, I3, 25, 32, 31, M, 44 and 49 for generating respectivelythe sub-fundamental, sub-third, fundamental, second, third, fourth,fifth, sixth and eighth harmonics. These generators are provided withpickup coils H2 and decoupling resistors RI I4 previously described withthe latter being connected to switch contact arms I I6 of the upper andlower manuals as well as the pedal clavier in the manner previouslydescribed, and as further illustrated in the above mentioned Patent No.1,956,350. The preset keys I40, I4I operate switches I44 in the mannerpreviously described.

In addition to the playing keys and preset keys there are provided threecontrol keys 280, 282, 284 for the upper manual and similar keys 28I,283 and 285 for the lower manual. The output system of the instrumentincludes two transmission channels designated as I and 2 in Fig. 2b.When key 280 is depressed the key switches 288 operated thereby willrespectively connect the bus bars I20--I 28 to sliding contactors 290associated with eight draw-bars 292. The contactor 290 maintains slidingcontact with a contactor 294 which is adapted to engage any one of aplurality of busses 296 which are respectively connected to the taps ofthe primary of a transformer 300 for the channel No. 1 of the outputsystem. Similarly, if key 282 is depressed to close its switches 302,the bus bars I20--I28 will respectively be connected to slidingcontactors 306 which are adapted to maintain contact with contactors 308while the latter make contact with any of a plurality of busses 3I0connected respectively to taps on the primary winding of a transformer3I2 forming part of the channel No. 2.

When the third control switch 284 is depressed the switches 3I4 operatedthereby respectively complete circuits from the bus bars I20-I28 toswitch arms 3I6 carried by a pivotal manually operable tablet 3I8. Whenthis tablet is swung downwardly as shown in Fig. 2b, the switch arms 3I6connect the bus bars I20-I28 respectively to slide contactors 290 sothat the signals on these bus bars are transmitted to the transformerasses-ea 399 of channel 'No. 1, with each partial of an amplitudedetermined by the position to which its associated drawbar 292 isadjusted. on the other hand, when the tablet 3; is swung upwardly thebus bars 129-428 are respectively connected to the slide contactors 396and thus the signals from these bus bars are transmitted to the primaryof transformer 312 of channel No. 2, and their amplitudes will likewisebe de-- termined by the setting of the drawbars 292. Thus. by simplyoperating the tablet M8 the tone signals present on the bus bars l29-l29may be made to be transmitted through either channel No. 1 or channelNo. 2. As will hereinafter appear, each channel may be adjusted to beeffective to add the vibrato effect to the signals or to transmit thesignals without this effect.

The control keys 28I, 283 and 285 are similarly connected to drawbars329 and tablet operated switches 322, the construction and the operationof these circuits being the same as are controlled by keys 289, 282 and294, as above described.

The secondary of transformer 399 is connected to a preamplifier 339while the secondary transformer M2 is connected to a preamplifier 33!.Each of these amplifiers may be provided with a volume control 332, 333of any suitable construction, these volume controls being preferablyoperated by a single expression pedal 334, although separate expressionpedals for each of these volume controls may be provided. Thepreamplifier 339 has its output coupled to a long artificial linevibrato apparatus 336 which preferably is provided with a control 338whereby the extent of the vibrato may be changed as well as a vibratochorus control. The output of preamplifier 33l is coupled to arelatively short artificial line vibrato apparatus 331, having asuitable on-off and extent control 339, and a chorus control 3. Asynchronous or other constant speed motor 344 drives the scanning platesof both of the vibrato apparatuses 338 and 339, so that the signalsappearing on their artificial lines will be picked up in phase andsynchronism with one another.

The vibrato chorus controls 349 and 34f may be of the type disclosed inPatent 2,509,923, granted May 30, 1950, upon my copending applicationSerial No. 653,195 filed March 8, 1946.

The output circuits of the two vibrato apparatuses are suitably coupledto an amplifier 345 which may drive a speaker 348.

The instrument shown in Figs. 2a and 2b is played in the customarymanner except that the organist has at his immediate control the abilityto change the tone from one having the vibrato to a similar tone withoutvibrato. Furthermore he has the ability to produce vibrato chorus inwhich both the vibrato and non-vibrato tone are superimposed to provideensemble tonalities.

By suitably wiring the harmonic combinations to the preset keys he mayalso produce tonalities in which the vibrato effect is on only some ofthe various harmonics, and in this way he can produce a great many newand very interesting musical effects. When using one of these mixednon-vibrato vibrato combinations he may alter and reverse the vibratoand non-vibrato effects on the various harmonics by operation of vibratocontrols 338 and 339. By interchanging the positions of these twocontrols he automatically changes the vibrato and non-vibratoarrangement on the preset combinations, that is, those partials whichwere previously vibrato now have no vibrato and vice-versa.

} By operation of keys 299 and 28l the organist may render the hand setdrawbars 292 and 329 capable of selective registration to transmit thesignal to channel No. l which has wide phase shifting characteristicsand is therefore adaptable for large vibrato effects. In a similarmanner operation of preset keys 282 and 293 causes the signals fromtheir associated bus bars to be transmitted to channel No. 2 under thecontrol of drawbars 292 and 329, which channel preferably introduceslittle or no vibrato. Thus having set the drawbars 292 and 329 toproduce a certain tone quality, this quality is quickly changed eitherto include the vibrato effect, or not. Operation of preset keys 284, 285enables the musician manually to select either channel No. l or channelNo. 2 to be coupled to the drawbars 292 and 329, by shifting the tabletselectors M8 and 322.

In the previously described embodiments of the invention the expressionpedal is illustrated as operating the volume controls for both channels.This is not necessary since a swell pedal may be provided for each ofthe volume controls so that the intensity of the tones produced underthe control of the keys of one manual may be varied with respect to theintensity of the tones produced under the control of the keys of theother manual.

In neither of these embodiments is it feasible to supply to theamplifier tone signals from a more or less separate auxiliary instrumentwhich is capable of supplying electrical tone signals containing avibrato. In some electric organs it is desirable to utilize the outputsystem of the organ for amplification and translating into sound thetone signals of the auxiliary instrument, such as those of chimes, harp,or bells, with an electric pickup, or an electric melody instrument suchas shown for example in the prior patent to Hammond et al. No.2,233,258. The auxiliary instrument may be controlled by switchesoperated by the organ playing keys and may be arranged so that thehighest of a number of simultaneously depressed keys will control thepitch of the tone signals produced. Since such instrument will usuallybe one capable of producing vibrato tone signals, it would beundesirable to have its signals pass through the vibrato apparatus ofthe organ. In such instruments in which the auxiliary or melodyinstrument is to be played in conjunction with the organ I prefer theoutput system shown in Fig. 4.

In this arrangement the output signal from a special matchingtransformer I59 (for the output of the swell or upper manual) isconnected to one pole of a single pole double throw switch 369, whilethe signal from the matching transformer [5| (for the great or lowermanual, and pedals) is transmitted to a similar switch 36L When theseswitches are in their upper full line positions as shown, they connectthe secondaries of the transformers I59 and Hi to a conductor 362,whereas when they are moved to their lower or dotted line positions theymake connections with a conductor 384. The conductor 362 is providedwith a suitable load and frequency response correction mesh comprisingR366, R398, L319, C312, variable volume control resistor R314 as well asseries capacitor C316 and resistor R319.

The output of the electrical melody instrument may be connected to theconductor 364 through a relatively high value (e. g. .5 megohm) decoupling resistor R389 and thus have its effective amplitude controlled bythe expression or volume control resistor R315, of a load and frequencyresponsive mesh similar to that connected to conductor 362.

The signal appearing on the conductor 362 is impressed upon the controlgrid of an amplifying pentode 382 through an input circuit including acapacitor C384 in series with resistors R386 and R388, the junctionbetween the latter resistors being connected to ground through a seriesresistor R390 and capacitor C392, while the junction between C384 andR386 is connected to ground through a grid resistor R394.

The conductor 364 is similarly connected to the control grid of pentode396, the circuit elements bearing similar reference characters. Thecontrol grids of pentode 382 and 395 and 396 are connected to theircathodes by capacitors C391.

In this embodiment of the invention it is practically necessary that thevariable volume control resistor R315, for the signal on conductor 364,be mechanically connected to the corresponding variable resistor R314,since these controls are not particularly associated with either manual.

The screen grid of pentode 382 is connected to the screen grid of apentode 383 by a coupling capacitor C399. The remaining elements of thecircuits associated with pentodes 382 and 383 may be identical withthose previously described with reference to the pentodes 240 and 24! ofFig. 1b. The output of the pentodes 382 and 383 is thus in push-pull,and is suitably coupled to a push-pull amplifier 400. The output of theamplifier 400 is connected to an artificial line vibrato apparatus 402having a control 404 to determine the extent of the vibrato. Thisvibrato apparatus may include a preamplifier and its output is connectedthrough a conductor 406 with the input circuit of a pentode 395. Thepentodes 395 and 396 and their associated circuit elements may beidentical with the pentodes 240 and 24I shown in Fig. lb. Their outputcircuits are likewise similar to those of pentodes 240 and MI and areillustrated as coupled to a power amplifier 242 and speaker 244. The Bsupply for the pentodes 382, 383, 395 and 396 is supplied from a 13+source through a suitable filtering mesh 408.

The output of the bass tone generators which is preferably transmittedthrough the output system without having the vibrato added will usuallybe connected to the taps on the primary winding of transformer Il.

The matching transformer I 5| for the lower manual and pedals may be ofconventional construction and the inductance of its secondary winding,at a frequency of approximately c. p. s., is such as to resonate withcapacitor C312 associated with the swell rheostat (and which iseffective in the circuit when the swell rheostat R315 is at minimumvalue). Because of this resonance effect a sharply rising bass frequencycharacteristic is attained at low volume, and this is highly desirablefor low pitch pedal tone. When the swell pedal is adjusted to maximumvalue of the resistor R315 the resistors R366 and R394 are effective toprovide a load which has a slight falling frequency characteristic atthe low frequency end.

In the operation of the instrument, the secondaries of transformers Iand I 5! are connected in parallel with each other by the switches 360and 36l, both when the vibrator is desired on both keyboards and when novibrato is desired on either keyboard. If these transformers were idealtransformers, that is, if they had infinite inductance, it would bepossible to connect the outputs of the two transformers in parallel to asingle load (resistors RI68 and R394) without noticeable losses.However, due to the fact that the grid and pedal matching transformerI5I is purposely designed to have an impedance comparable to that of aload provided by resistors R366 and R394 at the low frequency end, it isnecessary that means be provided for preventing noticeable losses in thebass frequencies when the two transformers I50 and I5I are connected inparallel. This is conveniently accomplished by making the secondary oftransformer I50 of higher inductance than the secondary of thetransformer I5I. If the inductances of the secondaries of transformersI50 and I5I are in the ratio of about 3 or 4 to 1 the losses in the bassrange will be less than 1 db when the two transformers are connected inparallel by the switches 360 and 36I. In practice it has been found thatmaking 6 of the 30 laminations of the core of transformer I50 of a highpermeability hydrafined Permalloy in place of the usual steellaminations, will sufliciently increase the inductance of the secondaryof transformer I50 to accomplish the desired result. When this is donethe loss factor, when the two transformers are connected in parallel, iskept within 1 db and is not greatly changed throughout the adjustmentsof the swell resistors R314 and R315 because of the high parallelimpedance of the secondary of transformer I 50. At frequencies otherthan the bass frequencies the 70,000 ohm load provided by resistors R366and R394 (each having a value of approximately 140,000 ohms) is thecontrolling impedance, and the parallel connection of the transformersproduces no substantial loss. The load resistors R366 and R394 are ofsufliciently low value that capacity effects due to the parallelconnection of the transformers I50 and |5I is kept within 1 db.

The loss of 1 db is not ordinarily undesirable in the rendition ofmusical compositions. It will be noted that when both of the outputs ofthe transformers I50 and I5I are connected to the output systemincluding conductor 362, the input of the non-vibrato system includingthe conductor 364 is loaded only by the 70,000 ohms provided byresistors R366 and R394, and the latter system may therefore be employedfor the amplification of electrical tone signals supplied by auxiliaryinstruments, such as chimes, harps etc. whose tonal effects are bestproduced without vibrato but the volume or expression of which is to becontrolled by the main expression pedal which controls the adjustment ofR314 and R315. The outputs of such instruments may be connected to theconductor 364 through a decoupling resistor R380 of relatively highvalue such as megohm. Inasmuch as the load provided by resistors R366and R394 is the controlling factor, the disconnection of bothtransformer secondaries from the conductor 364 will not have anyappreciable effect upon the volume of the tone si nals introduced throuh the decoupling resistor R380 from an auxiliary instrument. Thus thevolume of the acoustic si nal produced is substantially the same whethernone, one, or both of the secondaries of transformers I50 and I5I areconnected to the conductor 364.

Inasmuch as the low bass frequencies will not be transmitted efficientlythrough the transformer I 50 the connection of the secondary oftransformer I5I in parallel with the secondary of transformer I50 doesnot have any important effect.

From the generalized description of Fig. 3, as well as from thedescription of the specific em- 'bodinrents o! the .mventiomitwillzappear that" the invention'may b'e embodied-in alarge variety offorms. For example it is not essential that the artificial line vibratoapparatus of .my aforesaid Patent .No. 2,382,413 be employed in'thesystem.

Instead, :a vibrato phase shift apparatus operating acoustically andemploying 'theDoppler eflect may :be'used. Systems of this type :arediagram- 364 and selectively operated acoustic vibrato Ipparatuses I85and 465. Each of the vibrato apparatuses 365, 868 may consist ofrotating or oscillating elements in the form of vanes or hormllocatediinfront of the speaker so as cause apparent acoustic displacement of thesource of sound, thereby to produce the vibrato effect by direct phasemodulation of thesound waves. A vibrato apparatus of this typeassociated with a phonograph is shown in a patent to :Myers 647,147granted April 10,1900. The mechanical rotating or oscillating part ofsuch apparatus may be remotely controlled from the console and may bedrivenlby an adjustable speed electric motor. The rotating oroscillating vanes or horns are preferably operated in the synchronism toprevent :partial cancellation of their effects. Thus the player may havethe vibrato effect added to the tones controlled by the switching meanslfll, or .to the tones controlled by the switching means 102, or both,and he may therefore add materially to the variety of musical eifectswhich may be produced from the tone signal generating system.

Since it is infrequent that the vibrato effect will be desired in thetones controlled by both of the key operated switch means, the apparatusmay be simplified and its cost lessened by employing the apparatusdiagrammatically illustratedin Fig. 6. For the sake of simplicityreference characters employed in the description of Fig. :5 are used "todesignate corresponding. parts of 6. In Fig. 16 there is associated withthe speaker 363 a continuously operated acousticvibrato apparatus 361.Itwill be noted, however, that the switching means IM and 102 may :beconnected to either the first output systom :36! or to the second outputsystem 862, 01 both :of the switch means 1M, I02 may be con nected to:either the first output system tfilxor the second output :system 362 asindicated by the full and dotted line arrows that connect these parts.In thesystem of the type shown in Fig. 6, the instrument, if it includesa pedal clavier, will employ a third playing key operated switchingmeans which may be directly and permanently'connected to the secondoutput system. Thustherba'ss notes controlled by'the pedal clavier willat 'all times. be produced by the speaker .36! without the addition ofthe vibrato effect. The second output system 862 and its speaker 364 maythus be designed to transmit efficiently and at high amplitude the bassfrequencies as well as the frequencies. controlled by the switchingmeans I01, I02, whereas the first output-system 361 andits speaker 36!maybe less powerful since these parts are never called upon to transmitmore than approximately 34 Yes much energy as may be required of thesecond output system 362 andits speaker .384. Also'by virtue of thisarrangement the continuously operated acoustic vibrato apparatus 361maybe relatively smallsince it never operates upon the very low pedalfrequencies.

From the foregoing it willappear that the invention is capable ofembodiment in a wide'variety of .forms, each embodying the fundamentalprinciple of utilizing a single source of constant tone frequencysignals and, under the control of key operated switching means,transmitting such signals through two different channels or outputsystems in such manner that a vibrato effect-may be introduced in thetones transmitted through at least one of these systems. The instrumentpreferably includes means for switching the signals so that the vibratoeffect may be added by either or both of the channels.

Due to the fact that the tone signals transmitted through the twochannels (one with and the other without the vibrato effect added) arederived from a single tone frequency source, the average frequencies ofthe tones to which the vibrato effect has been added will be the same asthe corresponding tones to which the vibrato effect has not been added.There can therefore be no slow beats which might otherwise occur ifthere-were'difierences between the average frequencies of the vibratotonesand the frequencies of the non-vibrato tones. Were such frequencydifference present, the introduction of the vibrato effect would greatlymagnify the acoustic beat phenomenon.

Prior to the present invention it has never been possible to producefrom a single acoustic generator, or electro-acoustic generator, :1single tone having some of its partials of sustained unvarying pitchwhile other partials have their pitch shifted to produce a vibratoeffect. This effect can however readily be obtained in either of the twoforms of the invention disclosed in this application merely by makingthe proper connections from the preset switches I to the desired busseswhich are connected to the output transformers of the two channels. Thismixed or differential vibrato effect has great musical charm because ofthe chorus-like effect which is otherwise perceived only when aplurality of conventional orchestral instruments are soundedsimulaneously.

It will be observed that except for the additional amplifier channelsand the necessary additional switching devices, the instrument containsonly the components of the usual electric organ of the'type shown in"the Hammond Patent No. 1,956,350. The number of generators, keycircuit-s, preset keys and the like need not be increased to incorporatethe present invention in an instrument of the prior art type. Thus thegreat improvements in tone qualities and versatility of the instrumentare obtained at a relatively small additional cost. If it were attemptedto produce equivalent effects without utilizing the principles of thisinvention, it would be necessary to provide two complete sets ofgenerators, one generating the tone signal without the vibrato and theother with the vibrato and it would be necessary to double the number ofswitches under each playing key and also to provide elaborate means formaintaining the generators of the two generating systems in like phase.It is questionable whether this could be accomplished in a commerciallypractical manner.

It will be understood that in the form of the invention shown in Figs.1a and 1b the secondary of the transformer I50 might be connecteddirectly (through a suitable network) to the control grid of pentodeI98, and similarly, the secondary of transformer I5I could be directlyconnected to the control grid of the pentode 2M through an appropriatecoupling network. Then the drawbar busses I48 and I49, instead of beingconnected directly to the taps of the primary of transformers I50, I5Irespectively could be provided with suitable double throw switches sothat these bus bars could be connected to the taps on either of thetransformer windings. The switch ing means could be in the form ofpreset keys I52, I53, except that the switch arms of the preset keyswould be respectively connected to the input taps of the transformersI50 and I5I', while they would make contact with the groups of bussesI48 and I49 respectively. The advantage of such latter construction isthat the busses I 68 for the pedals might be permanently connected tothe taps of the non-vibrato transformer IEI because it is usuallyundesirable to introduce the vibrato effect in the tones controlled bythe pedals. Signals from other tone generating systems might bepermanently or selectively connected to the input of the transformerI5I, such as microphones, melody instruments, etc. in which the organvibrato effect would be undesirable but which it nevertheless would bede sirable to control in intensity by the organ expression pedal.

While I have shown and described particular embodiments of my invention,it will be apparent to those skilled in the art that numerousmodifications and variations may be made in the form and constructionthereof, without departing from the more fundamental principles of theinvention. I therefore desire, by the following claims, to includewithin the scope of my ivention all such similar and modified forms ofthe apparatus disclosed, by which substantially the re sults of theinvention may be obtained by substantially the same or equivalent means.

I claim:

1. In an electrical musical instrument, the combination of a pluralityof generators, each generating an electrical signal of constantfrequency corresponding to a note of the musical scale, a plurality ofbus bars, playing key operated switches for respectively connecting saidgenerators with the bus bars, a pair of output channels, each channelhaving a transformer provided with a plurality of taps on its primarywinding, preset keys operable to connect said bus bars to preselectedtaps on either of said transformer primary windings, an artificial linevibrato apparatus coupled to the secondary windings of each of saidtransformers, said vibrato apparatuses being mechanically coupledtogether to operate in phase and in synchronism, means for selectivelyrendering either of said vibrato apparatuses effective to produce avibrato effect of predetermined extent in the signal supplied thereto,and means for amplifying and translating into sound the outputs of saidvibrato apparatuses.

2. The combination set forth in claim 1 in which there is a common meansfor controlling the volume of the output of the two channels.

3. The combination set forth in claim 1 in which the instrument includesa plurality of manuals and a plurality of drawbars, one for each partialfor each manual, and in which one of the preset keys is provided withconnections to render said drawbars effective.

4. The combination set forth in claim 1 in which there is provided aplurality of drawbars, each having means for selectively connecting oneof the bus bars to any one of the taps on either of the transformerprimary windings.

5. The combination set forth in claim 1 in which there are provided aplurality of drawbars, one for each of the bus bars, each drawbar havinga pair of sliding contactors respectively engageable with two series ofcontacts respectively connected to the taps of the two transformerprimary windings, and in which there is an independent manually operableswitch to connect the associated bus bar to either of the slidingcontactors.

6. In an electrical musical instrument, the combination of a pluralityof sources of electrical musical tone frequency signals, a pedal claviercomprising a plurality of keys, a plurality of playing keys forming twomanuals, a first and a second transformer, a load impedance, means forselectively connectingeither or both of the transformers to the loadimpedance, signal collector busses respectively connected to the primarywindings of said transformers, switches operable by the keys of onemanual to connect said sources to the collector busses associated withthe first transformer, and switches operable by the keys of the othermanual and pedal clavier to connect said sources to the collector bussesassociated with the second transformer, the second transformer having asecondary impedance comparable to the load impedance at the lowestfrequency of the signals controlled by the pedal operated switches, andthe first transformer having and impedance which is high with respect tothat of the second transformer at the lowest frequency of the signalscontrolled by the pedal operated switches, whereby there will be noappreciable attenuation of the tone signals respectively transmitted bythe two transformers whether they are connected singly or in parallel tothe load impedance.

7. In an electrical musical instrument having a generator of anelectrical signal of relatively constant musical tone frequency, avibrato apparatus capable of changing a constant frequency electricaltone signal supplied thereto into a tone signal incorporating afrequency shift vibrato, an output system coupled to said vibratoapparatus, and a plurality of playing key operated switching means, atleast one of the switching means being operable to couple the generatorto the vibrato apparatus to supply a tone signal to the latter, and atleast another of said switching means being operable to couple thegenerator directly to the output system.

8. The combination set forth in claim 7 in which both switching meansare operated by the same playing key.

9. The combination set forth in claim 7 in which the instrument includestwo manuals, and in which one of the switching means comprises switchesoperated by a playing key of one manual and the other switching meanscomprises switches operated by a playing key of the other manual.

10. The combination set forth in claim 7 in which the generatorgenerates a plurality of relatively constant tone frequencies usable tosupply partials for the production of a complex musical tone under thecontrol of a single playing key, and in which the switching meansoperates to couple the generators of some par tials to the vibratoapparatus and to cor t (J generators of the other partials directly 1output system.

11. In an electrical musical instrument having a plurality of generatorsof electrical signals of different relatively constant musical tonefrequencies, a pair of output channels, means associated with one of thechannels to introduce a frequency shift vibrato eifect in the musicaltones produced thereby, and a plurality of playing key operatedswitching means, at least one of the switching means being operable tocouple one of the generators to one of the out at systems and at leastanother of said switching means being operable to couple the samegenerator to the other output channel.

12. In an electrical musical instrument having a plurality of generatorsof electrical signals of different relatively constant musical tonefrequencies, a plurality of output channels, means associatedrespectively with said channels to introduce frequency shift vibratoeffects of different characters in the musical tones produced thereby,and a plurality of playing key operated switch means, one of the switchmeans being operable to couple one of the generators to one of theoutput channels and at least another of said switch means being operableto couple the same generator to another output channel.

13. The combination set forth in claim 12 in which the means associatedrespectively with the channels are constructed and arranged to introducevibrato effects of different extents.

14. The combination set forth in claim 12 in which the means forrespectively introducing the vibrato effects in the two channels differin the periodicity of the vibrato introduced.

15. The combination set forth in claim 12 in which the means associatedrespectively with the output channels to introduce the vibrato effectdiffer with respect to the periodicity and extent of the vibratosintroduced thereby.

16. In an electrical musical instrument having a plurality of generatorsof electrical signals of different relatively constant musical tonefrequencies, a pair of output channels, means associated with one ofsaid channels to introduce frequency shift vibrato effects in themusical tones produced thereby, a pair of matching transformers, thesecondaries of which have materially different inductance values, meansfor selectively coupling the matching transformers to the outputchannels, a pair of playing key operated switch means, one of the switchmeans being operable to couple one of the generators to one of thematching transformers and the other of said switching means beingoperable to couple the same generator to the other transformer.

17. In an electrical musical instrument including two playing manualsand having a plurality of generators of electrical signals of relativelyconstant musical tone frequencies, a vibrato apparatus capable ofchanging constant musical frequency electrical tone signals suppliedthereto into tone signals incorporating a frequency shift vibrato, anoutput system coupled to said vibrato apparatus, and a plurality ofplaying key operated switching means, the switching means operated bythe playing keys of at least one manual being operable to couplegenerators to the vibrato apparatus to supply tone signals to thelatter, and the switching means operated by the playing keys of at leastanother manual being simultaneously operable to couple the samegenerators directly to the output system.

18. An electrical musical instrument compris- 1 ing, a plurality ofgenerators of electrical signals different relatively constant musicaltone frequencies, pair of output channels, means associated with one ofthe channels to introduce a frequency shift vibrato effect in themusical tones produced thereby, and a plurality of groups of playing keyoperated switching means, the switching means of at least one of saidgroups being connected to couple the generators to one of the outputchannels, and the switching means of at least another of said groupsbeing connected to couple the same generators to the other outputchannel.

19. An electrical musical instrument comprismg a plurality of generatorsof electrical signals of different relatively constant musical tonefrequencies, a pair of output channels, means associated with one of thechannels to introduce a frequency shift vibrato effect in the musicaltones produced thereby, a plurality of groups of playing key operatedswitching means, means coupling the switching means to the generators,and selectively operable means coupling the switching means to either ofthe output channels.

20. An electrical musical instrument comprising, a plurality of manualsof playing keys, a plurality of generators of electrical signals ofdifferent relatively constant musical tone frequencies, a pair of outputchannels, means associated with the channels to introduce diiferentcharacteristic frequency shift vibrato effects in the musical tonesproduced thereby, a plurality of switching means operable by the playingkeys, means coupling the switching means to the generators, andselectively operable means for coupling the switching means to theoutput channels.

21. An electrical musical instrument comprising a plurality ofgenerators of electrical signals of different relatively constantmusical tone frequencies, a pair of output channels, means associatedwith one of the channels to introduce a frequency shift vibrato effectin the musical tones produced thereby, a plurality of groups of playingkey operated switching means, means coupling the switching means to thegenerators, means coupling the switching means of one group to oneoutput channel and means coupling the switching means of another groupto the other output channel.

JOHN M. HANERT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,877,317 Hitchcock Sept. 13,1932 2,147,948 Kent et al Feb. 21, 1939 2,274,370 Kent Feb. 24, 1942

